Connectors for tubes are known which have a hollow connector body and openings at one or both ends thereof for receiving an end of the tube(s). The connectors are typically provided with means for gripping the tube to prevent its retraction, and means for providing a seal (e.g. a fluid-tight seal such as a water-tight or gas-tight seal) between the tube and the connector body.
One common arrangement for holding the tube within the connector and providing a seal comprises a collet and an array of grab rings and sealing rings such as O-rings. The grab rings, which are typically formed of a metal material, have teeth which are inclined away from the end openings and which grip the surface of the tube. If an attempt is made to pull the tube out of the connector, the angle of inclination of the teeth means that they dig deeper into the wall of the tube and so prevent the tube from being retracted through the grab ring. The collet, which serves to hold the grab ring(s) and sealing ring(s) in place, is typically provided with a plurality of resilient arms which form a snap fit in lateral openings in the wall of the connector body and therefore cannot be retracted from the connector body without first depressing the resilient arms using a suitable tool.
Push fit connectors of the aforementioned type provide a generally very effective and secure means of connecting tubes together. However, they will only do so if the tubes are pushed in far enough to engage the gripping and sealing means correctly. If they are not pushed in far enough to make contact with and be gripped by the gripping means (e.g. the grab ring), then the joint formed between the connector and the tube may fail as soon as any axial tension is applied to the tube.